Polymeric materials have been used very widely in different widely, such as coating, construction, transport, etc. In order to improve the fire safety of polymers, series of fire retardants had been developed in the last 30 years. Halogenated fire retardants combined with antimony trioxide were regarded as efficient flame retardant to most of polymers, while they are facing the consideration of the environmental problems. The use of such fire retardants has been limited due to the environment concern. Therefore, development eco-friendly and green fire retardants are urgent and necessary.
Ammonium polyphosphate (APP) is widely used eco-friendly fire retardant to polymers due to its high contents of phosphorus (P) and nitrogen (N). However, it has low efficiency if it has been used only. Usually, it needs the char agent to improve the performance. Aiming to widen its applications in the polymer field, much work has been done in past 20 years, such as development of intumescent flame retardant (IFR) systems which needs three components: acid sources, blowing agent and carbonization agent. However, due to the incompatibility of three components, in most cases it would result in reducing the properties and performance.
European Patent No. 180795 (Werner et al.) showed flame retardant packages comprising microencapsulated ammonium polyphosphate within a melamine formaldehyde resin.
China Patent No. CN101429291A (Feng et al) disclosed microcapsule-coated modified ammonium polyphosphate. In comparison to untreated ammonium polyphosphate, the treated one owns good fluidity, compact and uniform coating.
U.S. Pat. No. 7,611,771 B2 (Kohei et al) disclosed the silicone resin was used to cover the polyphosphate compound, showing improved properties to the textile.
China Patent No. CN101570325A (Dai et al) disclosed ammonium polyphosphate were functionalized with silicone, which resulted in reduction in flammability of polymers.
EP Patent application (EP 0924166 A1) (Wang et al) described that ammonium polyphosphate were treated with triazine, which was improving the flame-retardant efficiency.
US Patent application (US20100168284 A1)(Gaggar et al.) disclosed a fire retardant composition comprising 40-66 wt % alkenyl aromatic resion, 9-33 wt % ammonium polyphosphate and 14-40 wt % starch and exhibited at least V-1 rating in UL94 test to the molded polymer.
(U.S. Pat. No. 8,834,750 B1) (Glenn, et al.) invented fire retardant compositions comprising clay and starch and uses thereof to protect structure and objects from fire.
In the paper (J. Mater. Chem. A, 2014, 2, 13955), Zhu-Bao Shao, et al, reported ethanolamine had been used to chemically modify ammonium polyphosphate via ion exchange reaction.
In the paper (Ind Eng Chem Res, 2011, 50, 713) Xin Wang et al., reported that adding 2.5 wt % starch to intumescent fire rertardant helped polylactic acid passed UL94 V-1 rating and LOI value at 28.5.
In the paper (J. Appl Polym Sci, 2014, 131, 41158) Gavgani et al., reported by addition of 10 wt % starch and 20 wt % intumescent fire rertardant to polyurethane increased the LOI value from 22 to 40 and UL94 V-0 rating.
In the paper (Ind Eng Chem Res, 2015, 54(48), 11944) Shuidong Zhang et al., developed oxidized corn starch and combined it with microencapsulated ammonium polyphosphate to epoxy resin, finding the final epoxy composites showed decreased peak of the heat release rate at 12.5 wt % additive.
In contrast to the previous arts, in this invention we disclose novel bio-based fire retardant derived from polyacrylamide grafted starch. Moreover, the present invention also provides its application, in particular in the coating field. In comparison to the traditional fire retardants and reported additives, the new compound in this invention owns: i) multi-fire retardant elements in one compounds based on the polyacrylamide grafted starch; ii) improved fire retardant performance compared to the physical blends of varied components. iii) Biobased and green fire retardants.